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• D-AFB has a simple structure and can easily satisfy QZS conditions. • Customizing the design of D-AFB to adapt to load requirements. • The experiment verified the reliability of replacing D-AFB. • Increasing the number of D-AFB can improve the carrying capacity. • The vibration isolator can stably adapt to load fluctuations within 10 %. There is an increasing demand for integrated small vibration isolators in precision sensing instruments and medical equipment. Therefore, a quasi-zero stiffness (QZS) vibration isolator with double-arc flexible beams (D-AFB) is proposed. The QZS isolator consists of D-AFB units, the base, platform, fixture, guide rail, and linear bearing. The static performance of D-AFB is analyzed using the FEA method, and the QZS condition is obtained. The harmonic balance method (HBM) and the pseudo arc length method (PALM) are used to solve the dynamic equations of the nonlinear system, and the analytical solutions of displacement transmissibility and Force transmissibility are derived. In theory, the initial frequency is 77.6 % lower than that of the equivalent linear system. The QZS characteristic of D-AFB is verified by static experiment, and the low-frequency isolation performance of the QZS isolator is verified by dynamic experiment under constant amplitude and constant acceleration excitation. The D-AFB has a simple structure and can easily satisfy QZS conditions. So the D-AFB can be customized according to load requirements. Multiple vibration isolation loads can be obtained by adjusting the assembly of the D-AFB. The QZS isolator can adapt to load changes within 10 % and has an isolation effect on vibrations above 4 Hz. The idea of designing a QZS isolator with D-AFB as an array unit has a good research prospect and great application value in meeting the requirements of miniaturization and integration. [Display omitted] [ABSTRACT FROM AUTHOR]

Ship vibration not only causes safety issues, but also easily generates noise pollution. Therefore, this paper introduces the quasi-zero stiffness (QZS) vibration isolator to solve the problem of low-frequency vibration. In terms of static analysis, this paper proposes a discretized beam constraint model (DBCM) to study the static properties of flexible beams with large deformation, and the finite element analysis (FEA) verifies the accuracy of DBCM. Regarding dynamic analysis, this paper combines the harmonic balance method (HBM) and the pseudo-arc length method (PALM) to analyze the dynamic response and explore the influence of excitation and damping ratio on the response stability. In addition, the performance of equivalent linear isolators is compared, revealing significant advantages of QZS isolator in terms of isolation bandwidth and peak transmissibility. The experimental data demonstrates that QZS isolator's initial isolation frequency (2.14 Hz) is 68.5% lower than that of linear isolators (6.79 Hz), and the isolation efficiency at 5.35 Hz can reach 90%, making it suitable for low-frequency isolation. Furthermore, experimental data validate the accuracy of the theoretical model and FEA. The static and dynamic theoretical models can optimize the structural parameters of flexible beams and serve as valuable inspiration and reference for designing and improving isolator. • The QZS isolator is composed of eight flexible beams and a linear spring. • DBCM can accurately calculate the nonlinear statics of flexible beams. • The QZS isolator has a wider isolation frequency band and lower transmissibility. [ABSTRACT FROM AUTHOR]

This study constructs a market area evolution model from the perspective of economic subject and location matching under the hypothesis of non-homogeneous space. It is proved that transportation development can reduce transport costs, which is closely related to location factor endowments. As such, we believe that when analyse the economic impact of new means of transportation, both overall analysis and different line analysis should be taken into account. Therefore, the economic impact of high-speed rail were studied by DID and PSM-DID methods. The results show that China's high-speed rail construction has a positive effect on economic growth and will become an important force in reshaping the organization of China’s spatial economy. However, the effect is different for different high-speed rail lines. Thus, Chinese government needs to fully consider the economic impact of high-speed rail. In addition, the government needs to formulate a high-speed rail economic belt plan in accordance with the characteristics of different rail lines. Furthermore, China needs to adjust its regional development strategy and regional policies accordingly, because the role of high-speed rail is mainly depends on whether a location has the necessary conditions to achieve the desired effect. Therefore, a city should adjust and recombine the local factor endowment to align with high-speed rail if it wants to capitalize on the new high-speed rail. Otherwise, the introduction of high-speed rail likely to adversely impact economic growth, which make the city a peripheral city. [ABSTRACT FROM AUTHOR]

Objective With the growing need for reliable and durable upper arm hemodialysis access, we sought to compare the performance of a novel modified nontransposed brachiobasilic arteriovenous fistula (mNT-BBAVF) with that of the more traditional brachiocephalic arteriovenous fistula (BCAVF). Methods Briefly, to construct an mNT-BBAVF, an incision is made on the ulnar side of the elbow. The brachial artery and basilic vein are then isolated, and a side-to-side anastomosis is performed without transposition of the basilic vein. Next, the proximal basilic vein and the perforating veins within the surgical field are ligated. In this study, we retrospectively reviewed the medical records of all patients who underwent either an mNT-BBAVF or a BCAVF between January 2011 and October 2014 to compare 1-year primary unassisted patency, cumulative patency, and complications. We also examined hemodynamic parameters of vessels in each fistula type. Results We identified a total of 84 patients: 45 had a BCAVF, and 39 had an mNT-BBAVF. The two groups were well matched for baseline characteristics. Maturation rates at 1 month were 97% for mNT-BBAVF and 96% for BCAVF. The 1-year primary unassisted patency was significantly higher in the mNT-BBAVF group than that in the BCAVF group (87% vs 67%; hazard ratio, 2.86; 95% confidence interval, 1.11-6.40; P = .03), although cumulative patency did not differ (90% vs 73%; hazard ratio, 2.80; 95% confidence interval, 0.98-6.96 ; P = .06). There were no differences in thrombosis, failure of maturation, bleeding, steal syndrome, arm swelling, aneurysm, and stenosis between the two groups during the 12-month study. Importantly, diameters and blood flow volumes of the proximal cephalic vein, distal cephalic vein, and distal basilic vein in patients who received an mNT-BBAVF increased significantly after 12 months. All three vessels met the Kidney Disease Outcomes Quality Initiative (KDOQI) criteria for fistula maturation and were available for dialysis cannulation, whereas only the proximal cephalic vein in the BCAVF group met the maturation criteria and could be used for cannulation. Conclusions mNT-BBAVF appeared to be an effective alternative to BCAVF for upper arm hemodialysis access. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen evolution (PHE) is an attractive green way to produce clean energy. Zeolite-supported titanium dioxide (TiO 2) offers a cost-efficient pathway to prepare an efficient and recyclable photocatalyst for PHE. As known, zeolite has an excellent cation exchange capacity, and the exchangeable cations show considerable influence on its properties. However, the effect of exchangeable cations within zeolite-supported TiO 2 photocatalysts on their PHE activity remains unclear. Here, we prepared a series of zeolite LTA-supported TiO 2 photocatalysts (TXA, X = Na, K, Ca) with various cations (Na+, K+, Ca2+) inside the zeolite and investigated the effect of cations on their PHE activity. The results demonstrated that all TXA photocatalysts exhibit significantly enhanced PHE activity, and TCaA shows the highest hydrogen evolution rate, which is 3.84 times higher than that of P25. According to experimental results, TCaA possesses a higher solid-acid concentration and a larger surface area, which provides more proton sources and active sites for PHE, facilitates charge separation, and reduces photogenerated electron-hole pair recombination. We believe this work will offer a new exploration strategy for regulating the PHE performance of zeolite-supported TiO 2 -based photocatalysts and shed new light on the rational design of cost-efficient PHE catalysts. [Display omitted] • Cation-exchanged LTA zeolites-supported TiO 2 were prepared for PHE catalysts. • Zeolites-supported TiO 2 photocatalysts show significantly enhanced PHE efficiency. • CaA-supported TiO 2 exhibits an HER rate of 3.84 times higher than pristine P25. • The improvement mainly stemmed from high specific areas and solid-acid sites. • The higher solid-acid concentration provides more proton sources for PHE. [ABSTRACT FROM AUTHOR]

Highlights: [•] Metakaolin-based geopolymer is applied to detoxify and immobilize COPR. [•] Preferable sodium sulfide addition was determined according to Cr leachability. [•] The product prepared has a relatively high compressive strength. [Copyright &y& Elsevier]

Macrophages play pivotal roles in immunity, hematopoiesis, and tissue homeostasis. In mammals, macrophages have been shown to originate from yolk-sac-derived erythro-myeloid progenitors and aorta-gonad-mesonephros (AGM)-derived hematopoietic stem cells. However, whether macrophages can arise from other embryonic sites remains unclear. Here, using single-cell RNA sequencing, we profile the transcriptional landscape of mouse fetal placental hematopoiesis. We uncover and experimentally validate that a CD44+ subpopulation of placental endothelial cells (ECs) exhibits hemogenic potential. Importantly, lineage tracing using the newly generated Hoxa13 reporter line shows that Hoxa13 -labeled ECs can produce placental macrophages, named Hofbauer cell (HBC)-like cells. Furthermore, we identify two subtypes of HBC-like cells, and cell-cell interaction analysis identifies their potential roles in angiogenesis and antigen presentation, separately. Our study provides a comprehensive understanding of placental hematopoiesis and highlights the placenta as a source of macrophages, which has important implications for both basic and translational research. [Display omitted] • Single-cell transcriptional atlas of placental hematopoiesis in mouse embryos • Identification of a subset of placental ECs with hemogenic potential • Hoxa13 -mediated fate mapping of macrophage de novo generation from ECs • Transcriptomic characterization of HBC-like cells in fetal placental labyrinth Using single-cell RNA sequencing and lineage tracing, Liang et al. profile the transcriptional landscape of mouse fetal placental hematopoiesis and uncover that Hoxa13-labeled ECs can produce placental macrophages, named Hofbauer cell (HBC)-like cells, highlighting the placenta as a source of macrophages. [ABSTRACT FROM AUTHOR]

• NK cells are activated rather than suppressed in PQ-induced lung injury. • The NK cells are reduced in acute PQ poisoning model. • Depletion of NK cells in vivo attenuates PQ-induced lung injury. • Depletion of NK cells reverses the PQ induced-macrophages polarization. Acute lung injury is the main causative factor in paraquat dichloride (PQ)-induced mortality. The innate immune system-triggered detrimental inflammatory cascade plays a vital role in PQ-induced acute lung injury. However, the role of natural killer (NK) cells, which are essential for innate response, in PQ-induced acute lung injury remains largely unknown. Here, we found that in an acute PQ poisoning model, depletion of NK cells attenuated PQ-induced lung injury by inhibiting macrophage polarization towards the M1 type. Specifically, the percentages of NK cells were reduced in the lung, spleen, and peripheral blood in a murine model of acute PQ poisoning. NK cells were aberrantly activated, evidenced by upregulation of the activating markers CD69, CD107a, and NKG2D and downregulation of the inhibitive marker KLRG1. Further, NK-specific depletion in mice greatly prolonged the survival time and ameliorated reactive oxygen species-induced damage following PQ treatment compared with the control group. Importantly, NK cell depletion alleviated macrophage and neutrophil infiltration in the lung and reversed PQ induced-macrophage polarization towards the pro-inflammatory M1 type. Our study demonstrates a crucial role of NK cells and NK cell-to-macrophage interaction in PQ-induced acute lung injury. [ABSTRACT FROM AUTHOR]

In vertebrates, hematopoiesis occurring in different niches is orchestrated by intrinsic and extrinsic regulators. Previous studies have revealed numerous linear and planar regulatory mechanisms. However, a multi-dimensional transcriptomic atlas of any given hematopoietic organ has not yet been established. Here, we use multiple RNA sequencing (RNA-seq) approaches, including cell type-specific, temporal bulk RNA-seq, in vivo GEO-seq, and single-cell RNA-seq (scRNA-seq), to characterize the detailed spatiotemporal transcriptome during hematopoietic stem and progenitor cell (HSPC) expansion in the caudal hematopoietic tissue (CHT) of zebrafish. Combinatorial expression profiling reveals that, in the CHT niche, HSPCs and their neighboring supporting cells are co-regulated by shared signaling pathways and intrinsic factors, such as integrin signaling and Smchd1. Moreover, scRNA-seq analysis unveils the strong association between cell cycle status and HSPC differentiation. Taken together, we report a global transcriptome landscape that provides valuable insights and a rich resource to understand HSPC expansion in an intact vertebrate hematopoietic organ. • A spatiotemporal transcriptome analysis of HSPCs and their niche in development • Generation of a 3D transcriptional atlas of a zebrafish hematopoietic organ • Characterization of regulatory network among hematopoietic niches and progenitors • Analysis of cell cycle-associated differentiation of progenitor cells In this work, Xue et al. establish a 3D atlas of zebrafish caudal hematopoietic tissue and reveal mechanisms underlying HSPC expansion in an intact hematopoietic organ by multi-dimensional RNA-seq. [ABSTRACT FROM AUTHOR]

In this paper, Ni–SiC nanocomposites were deposited on Q235 steel substrates by magnetic pulse electrodeposition (MPED) technique. Microstructures, compositions and microhardness values of obtained composites were determined by scanning electron microscopy (SEM), scanning probe microscopy (SPM), X-ray diffraction (XRD), and triboindenter in-situ nanomechanical testing. Results showed S-30 nanocomposites with fine, compact and uniform structures consisting of fine nickel grains (average size: 381.7 nm) and SiC nanoparticles (average size: 34.2 nm). For SiC particle size of 30 nm, diffraction peaks of Ni and SiC appeared wide with low intensity, indicating S-30 nanocomposites with small sized Ni grains and SiC nanoparticles. Largest TiN content reaching 10.59 wt% was embedded in S-30 nanocomposites prepared at SiC particle size of 30 nm. Final depths of S-30 and S-200 composites were estimated to 15.1 μm and 24.8 μm, respectively. Wear and corrosion properties of Ni–SiC nanocomposites were then investigated. After corrosion testing for 24 h, the weight losses of S-200, S-80 and S-30 composites were recorded as 1.67, 1.44 and 0.95 mg, respectively. Under the same wear experimental conditions, S-200 composite presented the highest mass loss while S-80 composites displayed the lowest mass loss. By comparison, wear mass loss of S-30 nanocomposites was only 37.1 mg. [ABSTRACT FROM AUTHOR]

Abstract Pure Ni coating and Ni–SiC nanocoatings were deposited on mild steel substrates through magnetically assisted pulse electrodeposition (MAPED) from Watts-type nickel bath containing SiC nanoparticles. The microstructures, compositions, microhardness characteristics and wear properties of the coatings were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), triboindenter in-situ nanomechanical, and wear testing. The results indicated that the Ni–SiC nanocoatings deposited at 0.6 T exhibited exiguous and uniform morphologies with average sizes of Ni and SiC estimated to 45.4 nm and 28.5 nm, respectively. The (1 1 1), (2 0 0), (2 2 0) and (3 1 1) planes of nickel grains clearly appeared in pure Ni coating and Ni–SiC nanocoating. The Ni–SiC nanocoating prepared at 0.6 T had the highest average microhardness of 878.60 HV. Also, the ultimate depths of pure Ni coating and NS-3 nanocoating were identified as 32.9 µm and 18.2 µm, respectively. On the other hand, pure Ni coating displayed elevated weight mass losses whereas the other three MAPED-deposited Ni–SiC nanocoatings had smaller losses under similar wear testing parameters. In particular, the weight loss of Ni–SiC nanocoating was measured as 42.2 mg at magnetic density of 0.6 T. Finally, the NS-3 nanocoating suffered slight wear while NS-1 and NS-2 nanocoatings were severely destroyed by the ball during wear testing measurements. Therefore, NS-3 nanocoating resulted in the best wear resistance. [ABSTRACT FROM AUTHOR]

Industry 4.0 realizes intelligent interconnection through the sensor group of the Internet of Things. A key challenge is to achieve the self-powering of sensors and stable operation of precision instruments. This paper introduces a dual-functional structure (VIPEH) integrating energy harvesting (EH) and vibration isolation (VI) based on the quasi-zero stiffness (QZS) piezoelectric mechanism. The paper analyzes the nonlinear statics of piezoelectric flexible beams under large deformations and conducts parametric analysis. A nonlinear dynamic model with electromechanical coupling was developed to investigate the impact of mechanical and electrical parameters on the system's dynamic bifurcation behavior, EH, and VI performance. Finally, an experimental setup is created to evaluate the VIPEH's characteristics. Sweep frequency excitation experiments demonstrate that the initial isolation frequency of VIPEH is lower than 1.4 Hz. The important thing is that VIPEH can still power the sensor based on the isolation frequency, and the output power of a single piezoelectric material can reach 3.19 mW. This not only enables the isolation of low-frequency vibrations but also presents a highly promising application for achieving self-powering in sensor clusters within the context of Industry 4.0 and the IoTs. • VIPEH based on quasi-zero stiffness piezoelectric mechanism is proposed. • VIPEH achieves energy harvesting while isolating low-frequency vibrations. • The output power can reach 3.19 mW. • The initial vibration isolation frequency of VIPEH is less than 1.4 Hz. [ABSTRACT FROM AUTHOR]

• Reactive MD simulation was performed for oil-water separation with SWCNTs. • Various oil components exhibits different tendency for adsorption. • All considered oil components were adsorbed up to 0.8 ns of simulation time. • DFT-D3 revealed oil molecules were physisorbed onto CNTs with various strength. • Hydrophobicity plays key role in adsorption of oil molecules on CNT surface. The treatment of oily wastewater has drawn much attention due to environmental and human health challenges. Among several techniques and materials developed to mitigate the contamination of oily wastewater, the nanostructured materials for effective adsorption and separation came into the limelight. Owing to their high specific area and nanosized structure, CNTs have demonstrated inclusive utilization as superior materials for selective adsorption. Here, we present molecular origin of oil-water mixture separation by SWCNTs. We used reactive MD simulation to explain scientifically the separation mechanism of considered mixture at molecular scale. It was shown that small hydrocarbons tend to migrate toward the nanotube surface faster than large counterparts do and whole components were adsorbed on the CNT surface up to 0.8 ns of simulation time. This is due to the different hydrophobicity tendency associated with each oil components that has also been addressed by MD simulation. DFT-D3 calculations showed that interaction nature of adsorbed oil molecules onto the nanotube surface was typical for the physisorption. Furthermore, the accuracy of current methods has been validated by experimental and theoretical data. Our simulation findings provide a well-founded understanding for adsorption and separation of oil-water mixture by carbon based nanostructured materials. [ABSTRACT FROM AUTHOR]

Ag nanoparticles decorated urchin-like SrTiO 3 particles were synthesized by Atomic Layer Deposition (ALD). The morphology and crystal structures of SrTiO 3 and SrTiO 3 /Ag particles were determined by SEM, TEM, and XRD. The specific surface area of the samples was studied by N 2 adsorption/desorption. Finally, the photocatalytic activity of SrTiO 3 and SrTiO 3 /Ag particles was determined by the decomposition of RhB dye. The results indicated that when the ALD deposition cycle was 20, the SrTiO 3 /Ag composite showed the best photocatalytic performance, which was due to the increased electron/hole separations. Moreover, post-annealing could further increase the photocatalytic activity of SrTiO 3 /Ag, which could be explained by the increased interaction and decreased charge transfer resistance between SrTiO 3 and Ag. [ABSTRACT FROM AUTHOR]

Geopolymers are a new class of green high-strength aluminosilicate materials, which generally maintain an amorphous structure due to the limitations related to their chemical compositions and reaction conditions but possess the ability to form molecular sieves. In this work, the in-situ transformation of geopolymers into self-supporting NaX zeolite monoliths of relatively large sizes was examined under hydrothermal conditions and various parameters of the synthesis process were optimized. The obtained results indicated that the optimal transformation conditions for geopolymers with a Si/Al ratio of 4.0 are as follows: precursors composed of metakaolin and modified industrial sodium silicate with a Na 2 O/SiO 2 molar ratio of 1.0, H 2 O/Na 2 O molar ratio of 70, hydrothermal synthesis time of 18 h and a temperature of 90 °C. According to the obtained X-ray diffraction (XRD) data, the synthesized NaX Monoliths exhibited characteristic reflections consistent with those of standard NaX zeolites and possessed high degrees of crystallinity, while scanning electron microscopy revealed that the produced molecular sieves exhibited well-defined morphology. In addition, the zeolitic monoliths exhibited excellent compressive strength for potential practical applications. [ABSTRACT FROM AUTHOR]

A new type of ionic liquid was synthesized from lignin, tetrabutylphosphorus hydroxide, and benzotriazole, and its potential utility as a water-based lubricating additive was studied by comparing the performance of water containing the lubricating additive with that of water. The additive not only decreases the friction and wear of water on steel but also decreases the corrosive effect of water on steel, and improves the utilization rate of lignin, which is difficult to use. The mechanistic analysis of the lubrication in the presence of the ionic liquid revealed that a protective film containing nitrogen is formed on the surface of the steel/steel friction pair, which blocks direct contact of the friction pair and thus induces excellent tribological properties. [Display omitted] [ABSTRACT FROM AUTHOR]

A kind of oil-soluble dopamine-cholesterol compound (DA) is synthesized through molecular design. We performed solubility tests and thermogravimetric analysis (TGA) of PAO 10 and DA composition. The tribological properties of DA were investigated in different concentrations. Tribological results test showed that DA has excellent tribological properties. When the content of DA in PAO 10 reaches 3%, it has the most excellent tribological properties under room temperature (RT). The components of the friction interface was analyzed by the use of time-of-flight secondary spectroscopy (TOF-SIMS), X-ray photoelectron spectroscopy (XPS) and energy-dispersive spectrometer (EDS) in order to have a deeper knowledge of the tribo-chemical reaction mechanism of DA composition. The tribo-chemical film composed of nitrates, hydroxides, cyanides. • We synthesized a new green dopamine-cholesterol lubricant additive (DA). • DA molecules have excellent solubility stability and adsorption properties. • DA significantly enhances tribological performance of steel/steel friction pairs. • Generated protective film provides anti-friction and anti-wear properties. [ABSTRACT FROM AUTHOR]

The air-fuel mixture preparation in pilot spray-ignited natural gas engines is primarily dominated by piston bowl profiles and fuel injection strategy. Piston bowl geometry is regarded as the crucial point in controlling engine pollutant emissions. In the present work, the SAGE combustion model was applied coupled with a general reaction kinetic mechanism. The engine model was validated with experimental data achieved from a Cummins ISX 400 engine, and good agreement between predicted and measured in-cylinder pressure and heat release rate was obtained. The influence of various piston bowl designs, including Mexican-hat geometry, double-lip geometry, bow geometry, and toroidal geometry, on the combustion process, engine performance, and pollutant emissions of a high-pressure direct-injection natural gas engine have been studied and analyzed numerically. The present study confirms the benefit of the piston bowl design as a beneficial tool to enhance the performance and pollutant emissions of the pilot diesel-ignited natural gas engine. Results showed that different chamber shapes slightly influence the combustion initiation, and the difference in in-cylinder pressure presents noticeable as the combustion continues. A higher turbulent kinetic energy improves the flow movement and facilitates the mixture formation in the cylinder. However, the combustion behavior is unwished caused by the improper injection angle of natural gas. Increasing the recess depth of combustion chambers reduces NO x formations at the price of sacrificing fuel economy. For the bow combustion chamber design, the NO x emission declined by 31.1%, while the indicated specific fuel consumption increased by 5.5% compared with the original engine. Although the indicated mean effective pressure and specific fuel consumption of the optimal double-lip geometry almost remain the same, NO x emissions can be reduced by 16.7% compared with the base design. [Display omitted] • >Mexican-hat, double-lip, bow, and toroidal combustion chambers for pilot diesel-ignited natural gas engines are proposed. • >Increasing bowl depth is conducive to improving air/fuel mixing and lower emissions. • >Improvement in combustion allowed the bow combustion chamber to reduce HC and CO without altering NO x. • >Double-lip combustion chamber design reduces NO x emissions by 16% without sacrificing engine performance. [ABSTRACT FROM AUTHOR]